The present invention relates to a patterned magnetic media, and more particularly to a patterned media having variations in bit-island sizes that allows for the encoding of track identification (ID) information.
Disc drives are typically organized into a plurality of concentric tracks on one or more disc surfaces. As the disc spins, a magnetic transducer positioned over a particular concentric track senses magnetic transitions along the track. In response to the sensed magnetic transitions, the transducer head is able to retrieve user data stored on the concentric tracks.
Accurate retrieval of user data requires accurate positioning of the transducer head over the desired track. To this end, disc drives are typically encoded with servo sectors that uniquely identify each concentric track on the disc surface. The surface of a disc is therefore divided into data fields capable of storing user data and servo fields used to identify individual tracks. Servo fields are oftentimes positioned at regular intervals around the circumference of the disc, extending in a wedge-like fashion from the center to the outer circumference of the disc.
However, including dedicated servo fields comes at the expense of user data capacity as servo sector fields cannot be written with user data. Extensive work has been done in the field of minimizing overhead associated with servo fields in an effort to allocate more space on a disc to storing user data. A system that removes the need for dedicated or embedded servo fields would therefore be beneficial in improving the storage capacity of disc drives.